1. Field of the Invention
This invention relates to a method for allocating a call in a CDMA (Code Division Multiple Access) base station, and more particularly to a method for allocating a call to lower a level of interference affecting adversely neighboring cells in a CDMA base station.
2. Description of a Prior Art
In a conventional CDMA mobile communication system, an amount (level) of interference affecting adversely neighboring cell was increased by power transmitted from a mobile station at a boundary between cells.
For the purpose of illustrating this, FIG. 1 shows a level of interference in a neighboring cell dependent on a distance between a mobile station and a base station.
As shown in FIG. 1, the farther a mobile station communicating with a service base station 21 of a current servicing cell 20 gets away from the base station 21, for example like case of a mobile station m1 31, the nearer the mobile station comes to a neighboring base station 11 of a neighboring cell 10. Therefore, transmission power required for the communication between the base station and the mobile station is more consumed.
To the contrary, as the service base station 21 and the mobile station grows close one another, for example like case of a mobile station m2 32, the mobile station grows far away to the neighboring cell 10, which results in the consumption of less transmission power.
A strength of such a transmission power required for the communication between the base station and the mobile station is attenuated with inverse proportion to the fourth power of the distance. Therefore, as the mobile station grows closer to the neighboring cell 10 and thereby the transmission power of the mobile station grew stronger, a level of interference affecting adversely the neighboring cell grows high. More specifically, there was the problem that the higher level of interference is, the less the maximum capacity of call in the neighboring cell.